1. Field of the Invention
The present invention relates to telecommunications, and, in particular, to network-based systems for providing local access to telephone customers.
2. Description of the Related Art
Under current U.S. law, a local exchange company (LEC) (e.g., Pacific Bell or Bell Atlantic) must provide local access connections for its current local-service customers (i.e., subscribers) who desire to become customers of a competitive LEC (C-LEC) (e.g., AT&T, MCI, as well as competitive access providers). That is, a LEC must be able to connect the loops of its current customers to the appropriate C-LEC switches.
Before 1980, most access loops to customers were copper pairs of wire contained in standard telephony cables. With simple copper access to customers, the connection of customers to C-LECs is a matter of connecting a customer's copper loop to the C-LEC's trunk facility which connects the LEC's office to the C-LEC's office. In the 1970s, the first electronic access loops were deployed by LECs as a cost-saving and service-improving alternative to copper. These systems account for about 20% of the access loops now found in the U.S., and up to 50% in certain LECs.
FIG. 1 shows a block diagram of part of the existing manner used for C-LEC interconnection using a conventional INA (integrated network access) network 100 conforming to existing standards used by the HFC2000.TM. Broadband Access System of Lucent Technologies, Incorporated, of Murray Hill, N.J. In network 100, central office 102 of a local exchange company provides access to the phones 104 of its local-access customers and C-LEC switches 106. Central office 102 comprises LEC switch 108, high-bandwidth access resource manager (HBARM) 110, and radio frequency (RF) distribution shelf (RFDS) 112.
In particular, central office 102 electronically interconnects calls originating at the phones 104 of the local-service customers, as well as calls terminating at those phones. An originating call is transmitted from user phone 104 to central office 102 via network interface unit (NIU) 114 and fiber node 116. Central office 102 transmits the originating call to the appropriate C-LEC switch 106 via one of a plurality of DS1 transmission links 118, where each transmission link 118 is, for example, a 24-line multiplexed T1 connection. Similarly, a terminating call is received by central office 102 from a C-LEC switch 106 via a transmission link 118 and then transmitted by central office 102 to the appropriate user phone 104 via fiber node 116 and NIU 114.
With electronic access systems, such as that in FIG. 1, each LEC central office is capable of handling a finite number of calls at the same time (i.e., the call-switching capacity of the LEC). This number, which includes both local-service calls between the LEC's customers as well as calls to or from customers for which the LEC is supplying the loop facility and a C-LEC is supplying local switching, is a function of the amount of hardware in the central office. In order to be cost-efficient, this number is typically less than the total number of local-service customers of the LEC. That is, the number of phones 104 in network 100 of FIG. 1 is greater than the number of calls that can be handled by central office 102 at any one time.
In order to provide access to a competitive LEC, a LEC typically permanently assigns a subset of its available access capacity to the C-LEC (i.e., nails up a fixed number of virtual channels called DS0 time slots) and charges the C-LEC rent accordingly, independent of how the C-LEC actually uses those virtual channels. A permanently assigned virtual channel is represented in FIG. 1 as a broken line from phone 104 to the appropriate transmission link 118. These virtual channels are permanently assigned to a C-LEC and are therefore always available. As such, the C-LEC's customers are always guaranteed of being successfully switched by the LEC's central office. By the same token, because a large number of the LEC's virtual channels may be permanently assigned to the C-LECs, the likelihood that the LEC's own customers will have trouble placing local-service calls may be greatly increased. As a result, the CLECs' customers may actually get better service from the LEC's central office than the LEC's own customers.
A LEC can solve this problem by purchasing more and more hardware for its central office, but this can be prohibitively expensive. It can also be terribly inefficient, especially since many of the virtual channels that are permanently assigned to the C-LECs may typically be unused at any given time.